1. Field of the Invention
The present invention relates to an electronic equipment of the structure having heat pipes capable of removing heat generated in electronic parts, and more particularly, to a computer having similar structure which is suitable for application to medium- and small-sized computers for use in work stations or the like, and a heat radiating device thereof.
2. Description of the Prior Art
In medium- and small-sized computers for use in work stations or the like, LSI chips making up a CPU have been recently changed from CMOS's into higher-speed ECL's and increased in density and integration to meet demands for high-speed data processing. With such a change in circuit system and a higher degree of integration of LSI chips, heat generated from the LSI chips is also drastically increased. Thus, how to efficiently remove the heat generated from the LSI chips and maintain the chip temperature at an appropriate level is a serious technical problem in ensuring reliability of computers.
Meanwhile, computers have a tendency to decrease in size from the desk-side type to the desk-top type and then to the lap-top type for enhancing values of commodities. Dealing successfully with those contradictory problems of radiating heat and reducing size is a key in developing in the next generation of medium- and small-sized computers.
As disclosed in Japanese Unexamined Patent Publication No. 57-136354, it is known to radiate heat generated in electronic parts such as LSI chips to the exterior through heat pipes. In the prior art referred to, electronic parts greatly generating heat are mounted via insulating sheets and insulating bushes on a flat heat transfer board having a heat pipe provided with heat radiation fins. Heat generated from those electronic parts highly generating heat is transferred successively to the insulating sheets, the insulating bushes, the heat transfer board, the heat pipe and finally to the heat radiation fins. Air is introduced to only the heat radiation fins from outside of a computer to remove the heat therefrom. Because heat exchange with the outside air is performed only in the space of the heat radiation fins, there is no need for introducing the outside air into the entire area of a computer housing, and highly efficient heat radiation can be achieved with a compact device.
Thus, the prior art is directed to reduce the size of the computer housing by transferring the heat generated by the electronic parts to the heat radiation fins through the heat pipe, and performing heat exchange collectively at the heat radiation fins to limit the heat exchange areas. Where heat is absorbed from a number of parts by the heat pipe through the heat transfer board as in the prior art, however, if too much heat is collected in the heat pipe, a working fluid sealingly enclosed in the heat pipe is completely evaporated and the heat pipe no longer fulfills its function. This phenomenon is referred to as dryout.
Further, where a heat collecting portion in which heat is absorbed into the heat pipe is relatively long in comparison with the entire length of the heat pipe, the working fluid condensed in a heat radiating portion of the heat pipe is evaporated before reaching the end of the heat collecting portion, so that the phenomenon of dryout is more likely to occur and the efficiency of heat transfer is lowered toward the outermost end of the heat collecting portion.